Expression Hand
Muting was introduced as a form of timbral and dynamic variation. This image shows the part of the hand used in palm muting. Palm muting is a versatile technique and must be applied carefully depending on the application. Muting is often used as a transient effect. That is, the expression hand can be moderated to add muting intermittently.
These images show three examples of the palm mute:
A. Crunching power chords – only the bass strings need to be muted
B. The palm is running along the entire bridge progressively muting all six strings to end the chord by extinguishing the sustain
C. Strumming while muting all six strings, requiring a different strumming action.
Crunching power chords
Crunching is a guitar technique that uses power chords and is used in many styles, including grunge music of the 1990s. The simplicity of power chord fingering was ideal as it limited the number of strings that needed choking, and it allowed participants to focus on finding the right amount of pressure to balance the subtle muffling of the mute effect, without choking the string and stopping all sound.
Extinguishing the sustain
The guitar will sustain the sound for a long time if the strings are not disturbed. Applying the expression hand to the bridge, as illustrated in Image B, and gently rolling the hand towards the neck brings the sustain to a gentle pose. This technique is most appropriate at the end of the song, though can be applied in other ways too. For example, by placing your hands across the strings firm enough to muffle but not firm enough to play a new note.
Strumming with all strings muted
Image C shows the expression hand strumming while also muting. Unlike Image A, this time a partial mute is applied across all strings, softening the timbre and volume, while allowing a subdued level of resonance. This method can be used intermittently in combination with the accents and rhythms discussed above to create an infinite array of textures. Muting all the strings also requires a different strumming action as the wrist is unable to move as freely when maintaining a full mute across all strings.
Slap strum
A slap strum is a percussive accent combining a heavy strum with the choking effect of a full mute on the strings rather than the bridge. Slap strums vary in intensity depending on the style and are often used to infuse energy into a strumming pattern Error! Reference source not found. features a backbeat pattern similar to Figure 84, however the slap strum is used instead of the accent.